Method and apparatus for cutting material



y 9, 1967 w. L. ROBERTS 3,319,053

METHOD AND APPARATUS FOR CUTTING MATERIAL Filed Sept. 14, 1962 23 7% U (v v r\ L r\ A A 8 l8 20 22 v 1 I Rd A 2 SIGNAL 32 GENERATOR l 2 d 1 g2 80/ V l 48 STRAIN GAGE arm/1v am;

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' 50 'MOTOf? 74 744 I V 78 I 1 senvo I AMPLIFIER J INVENTOR. WILLIAM L. ROBERTS Attorney United States Patent ()filice 3,319,053 Patented May 9, 1967 3,319,053 METHOD AND APPARATUS FOR CUTTING MATERIAL William L. Roberts, Murrysville, Pa., assignor to United States Steel Corporation, a corporation of Delaware 1F iled Sept. 14, 1962, Ser. No. 224,599 9 Claims. (Cl. 235--151.1)

This invention relates to a method and apparatus for cutting material according to weight and more particularly to cutting steel slabs, blooms and beans blanks. In a steel rolling mill it is customary, in order to obtain a finished structural member of a desired length, to cut the beam blank to a certain size before finishing. Whether the finished product is of the desired length depends upon the accuracy with which the unfinished blank is cut. If the size of the piece cut from the blank is too small the finished member will be too short and if the unfinished piece is out too large, waste occurs when the finished beam is cut to the desired size. Hereto-fore, it has been the practice to cut the blank in accordance with physical dimensions, but such technique has the disadvantage that accurate measurements cannot be made rapidly and the finished beam will be of improper length. The weight of a beam of known cross section and length is readily calculable so that, if the weight of unfinished blank is made equal to such calculated weight, the finished member will be of the desired length.

Therefore, it is an object of my invention to provide a method of cutting a section of known weight from a beam blank prior to finished rolling.

Another object is to provide apparatus which may be used in carrying out the method of my invention.

These and other objects will be more apparent after referring to the following specification and attached drawing, in which:

The single figure is a schematic view of the preferred embodiment of my invention.

Referring more particularly to the drawing reference numerals 2 and 4 indicate conventional roll tables upon which a slab, bloom or beam blank S having a length L may be transported. The tables 2 and 4 are provided with rolls 6 which are driven by conventional means, not shown. Roll table 2 is supported by legs 8 and 10 which have load cells 12 and '14 therein, respectively, and table 4 is supported by legs 16 and 18 having load cells 20 and 22 therein, respectively. The distance between load cells 12 and '14 is d and the distance between load cells 20 and 22 is d The distance between legs 10 and 16 is shown exaggerated and is very small with respect to distances d and d A conventional saw or shear 23 is disposed between the tables 2 and 4. Each leg 8, 10, 16, and 18 has its counterpart including a load cell on the side of tables 2 and 4 which is not visible. The load cells in the legs not shown are each connected in series-adding with the corresponding load cells 12, 14, 20 and 22. Each of the load cells 12, 14, 2t and 22 is connected to a conventional strain gage bridge 24, 26, 28 and 30, respectively. To the input of each bridge 24, 26, 28 and 30 is connected a signal, which may be in the form of a DC. voltage, from a signal generator 32.

The output of bridge 24 is connected to the input of a conventional servo amplifier 34 whose output is connected to a conventional DC. motor 36- having a shaft 368. To shaft 368 is attached an arm 38A of a potentiometer 38 and one side of an electro-mechanical clutch 40. The other side of clutch 40 is attached to a shaft 42 to which are attached arms 44A and 46A of potentiometers 44 and 46, respectively.

The output of bridge 26- is connected to a conventional servo amplifier 48 whose output is connected to a conventional DC. motor 50 having a shaft 508. To shaft 50S are attached arms 512A and 54A of potentiometers 52 and 54, respectively, and one side of an electromechanical clutch 56. A shaft 58 attached to the other side of clutch 56 is connected to arm 60A of a potentiometer 60.

Clutches 40 and 56 are engaged only when energized by a battery 62 through a switch 64. A battery 66 connected across potentiometer 38 is also connected to the input of servo amplifier 34. Arm 38A is also electrically connected to the input of servo amplifier 34. A battery 68 connected across potentiometer 52 is also connected to the input of servo amplifier 48. Arm 52A is also connected to the input of servo amplifier 48.

The output of bridge 28 is connected to a conventional strain gage amplifier 70 and the output of bridge 30 is connected to a conventional strain gage amplifier 72. Preferably, amplifier 72 has a higher gain than amplifier 70. A potentiometer 74 having an arm 74A is connected across the output of amplifier 72. One side of potentiometer 74 is connected to one output terminal of amplifier 70, the other output terminal of which is connected to arm 54A. A battery 76 is connected across potentiometer 54 and its positive terminal is also connected to one terminal of a voltmeter 78. The other terminal of voltmeter 78 is connected to arm 74A.

Arm 60A is connected to a potentiometer 80 across which is connected a battery 82. Arm 80A of potentiometer 80 is attached to a shaft 84 to which is also attached an arm 86A of a potentiometer 86. A battery 88 is connected across potentiometer 86, its arm 86A being connected to one terminal of a voltmeter 90. The other terminal of voltmeter 9th is connected to arm 44A. One side of potentiometer 80 is connected to one terminal of a resistor 92 having a resistance small with respect to the resistance of potentiometers 80 and 86. One side of potentiometer 86 is connected to one terminal of potentiometer 44 and to arm 94A of a potentiometer 94. A battery 96 is connected across potentiometer 94 and its positive terminal is also connected to one terminal of resistor 92. One side of potentiometer 46 is connected to one side of potentiometer 6 0. Normally open contacts 98C and 9801 of a switch 98 are connected across the input terminals of servo amplifiers 34 and 38, respectively.

The operation of my device is as follows:

After the beam blank S is transported onto the table 2 and the leading edge has been cropped off square by saw 23, the total force measured by load cells 12 and 14 will be equal to the weight of the beam blank S. That is,

in which P is the force measured by load cell 12, P is the force measured by load cell 14, and M is the weight of the beam blank S. If a fulcrum is considered to exist in line with load cell 12, then, under the condition of equilibrium,

M(d -L/2)=d F (2) in which d is the distance between load cells 12 and 14 and L is the length of the beam blank S. If the beam blank S is now transported a distance partially onto table 4 so that it rests on both tables 2 and 4, the following relationship exists:

blank S. Again considering a fulcrum to exist at load cell 12, the following relationship exist-s at equilibrium:

in which X is the amount that beam blank S has been transported to the right and d is the distance between the load cells 20 and 22. The distance between legs and 1 6 is very small compared with d and d and is neglected. If the weight of the piece to be cut from beam blank S is W and has a length X then,

X =WL/M (5) for a beam blank S of uniform transverse cross section. Equations 1 through 5 may be manipulated to produce the equation:

It is seen that each variable quantity on the right side of this equation is measured when the beam blank S is in its original position and that each quantity of the left side is measured when the beam blank has been moved to the right a distance X. Therefore, if the quantity on the right side of Equation 6 is measured and retained and the beam blank S is moved to the right until the left side of Equation 6 equals the retained value, the beam blank S will have moved a distance X at which point it may be sawed with the result that the piece cut off will have the desired weight W.

With the cropped beam blank 6 resting entirely on table 2 the output of bridge 24 is proportional to F and the output of bridge 26 is proportional to F The output of bridge 24 when applied to motor 36 through servo amplifier 34 will cause shaft 365 to rotate an amount proportional to the force F Switch 64 is closed so that clutch 40 is engaged and shaft 42 will also rotate an amount proportional to the force F The arms 38A, 44A and 46A will move proportionally to shafts 36S and 42 so that the positions of the arms on potentiometers 38, 44 and 46 are in identical positions proportional to the output of bridge 24. The output of bridge 26 when applied to motor 50 through servo amplifier 48 will cause shafts 50S and 58 to rotate an amount proportional to the force F Thus, the arms 52A, 54A and 60A will be positioned to correspond to the force F Before moving the blank 8 switch 64 is opened, thus breaking the circuit which energizes the clutches 40 and 56. Thus, slider arms 44A and 46A retain the position corresponding to F and slider arm 60A retains the position corresponding to F The slider arm 80A is adjusted so that a potential is established between slider arm 80A and resistor 92 that is proportional to the value of 2W or twice the desired weight of the piece to be sheared from the blank S. The resistance of the slide wire of potentiometer 46 between slider arm 46A and the terminal adjacent potentiometer 60 is proportional to F The resistance of the slide wire of potentiometer 38 between the slider arm 60A and the terminal adjacent potentiometer 46 is proportional to P Since these segments of otentiometers 46 and 60 are connected in series the resistance between slider arms 46A and 60A is proportional to P plus F The value of resistor 92 is small compared to that between the arms 46A and 60A and may be neglected so that the current flowing through resistor 92 is proportional to 2W/F +F and therefore the potential developed across the resistor 92 is also proportional to 2W/F -l-F 'By [means of potentiometer 94 and battery 96 a potential is established between the resistor 92 and the slider arm 94A corresponding to unity. Since the circuit is arranged so that this potential opposes that developed across resistor 92 the potential developed between conductors 97 and 108 will be proportional to F12+F14 This potential is applied to the potentiometer 44 so that the current through its slide wire is proportional to Since the position of slider arm 44A is proportional to F the potential developed between conductors 108 and 99 is proportional to Slider arm 86A is adjusted so as to obtain a potential proportional to 2W between conductors 100 and 102. By suitably arranging the polarities this potential is added to that developed between conductors 108 and 99 so that the potential on voltmeter is proportional to The outputs of amplifiers 26 and 28 as they appear on potentiometer 54 and amplifier 70 are added to the potential between point 104 and arm 74A. Thus, the potential on voltmeter 7 8 is equal to With the slab S in this position it is separated by the saw 23 to obtain a piece of the desired length. The switch 98 is then closed shorting the inputs to the amplifiers 34 and 48 so as to restore the motor shafts 36S and 508 to their zero position. With the clutches 40 and 56 still disengaged the slider arms 44A, 46A and 60A are returned to their zero positions. Switch 64 is then closed to energize clutches 40 and 56 and the switch 98 opened so that the system is prepared for another cycle of operatron.

While one embodiment of my invention has been shown and described it will be apparent that other adaptations and modifications may be made without departing from the scope of the following claims.

I claim:

1. Apparatus for cutting a portion of predetermined weight from a workpiece comprising a table for supporting said workpiece, first means spaced apart a known distance longitudinally of the table for measuring the force due to gravity exerted by said workpiece, a second table for supporting said workpiece in close proximity to said first named table, second means spaced apart a known distance longitudinally of said second table for measuring the force clue to gravity exerted by said workpieces, means for cutting the workpiece located approximately at the adjacent ends of said tables, and means responsive to the said measurements to determine the length of a predetermined desired weight of said workpiece extending beyond said cut ting means upon said second table.

2' Apparatus for cutting a portion of predetermined weight from a workpiece comprising a table for supporting said workpiece, first means spaced apart a known distance longitudinally of the table for measuring the force due to gravity exerted by said workpiece, a second table for supporting said workpiece in close proximity to said first named table, second means spaced apart a known distance longitudinally of said second table for measuring the force due to gravity exerted by said workpiece, means for cutting the workpiece located approximately at the adjacent ends of said tables, means for indicating the individual gravity forces on said first named spaced apart measuring means when said workpiece is supported entirely on said first table with the forward end thereof at said cutting means, means for indicating the individual gravity forces on all of said measuring means when said workpiece is supported partially by each of said tables, and means responsive to the said measurements to determine the length of a predetermined desired weight of said workpiece extending beyond said cutting means upon said second table.

3. Apparatus for cutting a portion of predetermined weight from a workpiece comprising a table for supporting said workpiece, first and second means spaced apart a known distance longitudinally of the table for measuring the force due to gravity exerted by said workpiece, a second table for supporting said workpiece in close proximity to said first named table, third and fourth means spaced apart a known distance longitudinally of said second table for measuring the force due to gravity exerted by said workpiece, means for cutting the workpiece located approximately at the adjacent ends of said tables, said first and fourth measuring means being remote from said cutting means and said second and third measuring means being adjacent said cutting means, means for obtaining a first voltage proportional to the gravity force on said first measuring means when said workpiece is supported entirely on said first table with the forward end thereof at said cutting means, means for obtaining a second voltage proportional to the gravity force on the second measuring means when said workpiece is supported entirely on said first table with the forward end thereof at said cutting means, means for obtaining a third voltage proportional to the where F is the first named voltage, P is the second named voltage and W is the said predetermined weight, means for obtaining a fourth voltage proportional to the gravity force on said second measuring means when said workpiece is supported partially by each of said tables, means for obtaining a fifth voltage proportional to the gravity force on said third measuring means when said workpiece is supported partially by each of said tables, means for obtaining a sixth voltage proportional to the gravity force on said fourth measuring means when said workpiece is supported partially by each of said tables, and means for positioning said workpiece at a position partially on each of said tables so that said summation voltage equals mama-Few where F is the fourth named voltage, P is the fifth voltage, P is the sixth voltage, d is the distance between said first named spaced apart measuring means and d is the distance between said second spaced apart measuring means.

4. The method of cutting a portion of determined weight from a workpiece which comprises resting the workpiece on a first table with the leading end of the workpiece at a known location with respect to a cutting means, measuring the forces due to gravity exerted by said workpiece at two positions spaced apart a known distance lon gitudinally of the first table with the workpiece in said location, correlating said force measurements with the said determined weight to obtain a summation figure, moving said workpiece longitudinally to a position where it is supported partially on said first table and partially on a second table, with the workpiece on both tables measuring the forces due to gravity exerted by said workpiece at two positions spaced apart a known distance longitudinally of the second table and also the force due to gravity exerted by said workpiece at the position on the first table adjacent said second table, relating said last named readings to the distances between the measuring positions and the summation figure, and moving the workpiece in accordance with said relationships to determine the length to be cut from the workpiece to obtain the desired weight.

5. The method of cutting a portion of determined weight from a workpiece which comprises resting the workpiece on a first table with the leading end of the workpiece at a known location with respect to a cutting means, measuring the forces due to gravity exerted by said workpiece at two positions spaced :apart a known distance longitudinally of the first table with the workpiece in said location, obtaining a summation figure with the workpiece in said position equal to where F is proportional to the force exerted by the workpiece on the entry end of said first table, P is proportional to the force exerted by the workpiece on the exit end of said first table and W is the said predetermined weight, moving the workpiece to a position where it supported partially by the first table and partially by a second table closely adjacent the exit end of said first table, and having means for measuring the forces due to gravity exerted by said workpiece at two positions spaced apart a known distance longitudinally of said second table, and stopping the workpiece at a position on both tables such that the summation figure will equal where P is proportional to the force exerted by the workpiece on the exit end of said first table, P is proportional to the force exerted by the workpiece on the entry end of said second table, F is proportional to the force exerted by the workpiece on the exit end of said second table, al is the distance between the forces F +F and d is the distance between the forces F and F 6. Apparatus for cutting a portion of predetermined weight from a workpiece comprising a table for supporting said workpiece, first means spaced apart a known distance longitudinally of the table for obtaining a first electrical signal proportional to the force due to gravity exerted by said workpiece, a second table for supporting said workpiece in close proximity to said first named table, second means spaced apart a known distance longitudinally of said second table for obtaining a second electrical signal proportional to the force due to gravity exerted by said workpiece, means for cutting the workpiece located approximately at the adjacent ends of said tables, and electrical means responsive to said signals for determining the length of a predetermined desired weight of said workpiece extending beyond said cutting means upon said second table.

7. Apparatus for cutting a portion of predetermined weight from a workpiece comprising a table for supporting said workpiece, a first pair of means spaced apart a known distance longitudinally of the table for obtaining a first electrical signal proportional to the force due to gravity exerted by said workpiece, a second table for supporting said workpiece in close proximity to said first named table, a second pair of means spaced apart a known distance l-ongitudinally of said second table for obtaining a second electrical signal proportional to the force due to gravity exerted by said workpiece, means for cutting the workpiece located approximately at the adjacent ends of said tables, means for obtaining third and fourth electrical signals proportional to the individual gravity forces on said first named spaced apart measuring means when said work is supported entirely on said first table with the forward end thereof at said cutting means, means for obtain ing fifth, sixth, seventh and eighth electrical signals proportional to the individual gravity forces on all of said measuring means when said work-piece is supported partially by each of said tables, and electrical means responsive to said electrical signals to determine the length of a predetermined desired weight of said workpiece extending beyond said cutting means upon said sec-nd table.

8. The method of cutting a portion of determined weight from a workpiece which comprises resting the workpiece on a first table with the leading end of the workpiece at a known location with respect to a cutting means, obtaining first and second electrical signals proportional to the forces due to gravity exerted by said workpiece at two positions spaced apart a known distance longitudinally of the first table with the workpiece in said location, relating said electrical signals to the said determined weight to obtain a third electrical signal, moving said workpiece longitudinally to a positionwhere it is supported partially on said first table and partially on a second table, with the workpiece on both tables obtaining fourth and fifth electrical signals proportional to the forces due to gravity exerted by said workpiece at two positions spaced apart a known distance longitudinally of the second table and also a sixth electrical signal proportional to the force due to gravity exerted by said workpiece at the position on the first table adjacent said second table, relating said third, fourth, fifth and sixth electrical signals to the distance between the measuring positions, and moving the workpiece in accordance with said relationships to determine the length to be cut from the workpiece to obtain the desired weight.

9. The method of cutting a portion of determined weight from a workpiece which comprises resting the workpiece on a first table with the leading end of the workpiece at a known location with respect to a cutting means, obtaining first and second electrical signals proportional to the forces due to gravity exerted by said workpiece at a first position adjacent the entry end of said first table and a second position a known distance from the first position adjacent the exit end of said first table respectively, obtaining a third electrical signal with the workpiece in said position equal to where F is proportional to the first electrical signal, P is proportional to the second electrical signal and W is a fourth electrical signal proportional to the said predetermined weight, moving the workpiece to a position where it is supported partially by the first table and partially by a second table closely adjacent the exit end of said first table, and stopping the workpiece at a position on both tables such that the third electrical signal will equal where F is a fifth electrical signal proportional to the force exerted by the workpiece on the exit end of said first table, P is a sixth electrical signal proportional to the force exerted by the workpiece on the entry end of said second table, P is a seventh electrical signal proportional to the force exerted by the workpiece on the exit end of said second table, d is an eighth electrical signal proportional to the distance between the forces F and F and d is a ninth electrical signal proportional to the distance between the forces F and F I References Cited by the Examiner UNITED STATES PATENTS 3,175,438 3/1965 Johnson 235-15133 X MALCOLM A. MORRISON, Primary Examiner. I. KESCHNER, Assistant Examiner. 

1. APPARATUS FOR CUTTING A PORTION OF PREDETERMINED WEIGHT FROM A WORKPIECE COMPRISING A TABLE FOR SUPPORTING SAID WORKPIECE, FIRST MEANS SPACED APART A KNOWN DISTANCE LONGITUDINALLY OF THE TABLE FOR MEASURING THE FORCE DUE TO GRAVITY EXERTED BY SAID WORKPIECE, A SECOND TABLE FOR SUPPORTING SAID WORKPIECE IN CLOSE PROXIMITY TO SAID FIRST NAMED TABLE, SECOND MEANS SPACED APART A KNOWN DISTANCE LONGITUDINALLY OF SAID SECOND TABLE FOR MEASURING THE FORCE DUE TO GRAVITY EXERTED BY SAID WORKPIECES, MEANS FOR CUTTING THE WORKPIECE LOCATED APPROXIMATELY AT THE ADJACENT ENDS OF SAID TABLES, AND MEANS RESPONSIVE TO THE SAID MEASUREMENTS TO DETERMINE THE LENGTH OF A PREDETEMINED DESIRED WEIGHT OF SAID WORKPIECE EXTENDING BEYOND SAID CUTTING MEANS UPON SAID SECOND TABLE. 